8-319 BLACK BUNA 90D BACK-UP RING

Ordered as HB90319, this is an AS568-319 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 1.037 in (26.34 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 1.457 in (37.01 mm). The back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

Buna-N (Nitrile) is widely chosen for low compression set under sustained load, reliable performance in both static and dynamic service. It resists many alcohols, water, and petroleum-based oils. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in automotive brake fluid or strong acids.

It sees regular use in automotive, general industrial maintenance, and construction equipment.

HB90319 ships individually. Unit weight is approximately 1.0612 g and nominal inside diameter is listed as 1 1/16 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.